Russian Doll Envelopes
Desicription
You have a number of envelopes with widths and heights given as a pair of integers (w, h). One envelope can fit into another if and only if both the width and height of one envelope is greater than the width and height of the other envelope.
What is the maximum number of envelopes can you Russian doll? (put one inside other)
Note:
Rotation is not allowed.
Example:
代码语言：javascript复制Input: [[5,4],[6,4],[6,7],[2,3]]
Output: 3
Explanation: The maximum number of envelopes you can Russian doll is 3 ([2,3] => [5,4] => [6,7]).Solution
代码语言：javascript复制class Solution {
public:
int maxEnvelopes(std::vector<std::vector<int>>& envelopes) {
std::sort(envelopes.begin(), envelopes.end(), [](std::vector<int> a, std::vector<int> b) {
if(a[0] == b[0]) {
return a[1] < b[1];
}
return a[0] < b[0];
});
int res = 0;
auto dp = std::vector<int>(envelopes.size(), 0);
for(int i = 0; i < dp.size(); i ) {
dp[i] = 1;
for(int j = 0; j < i; j ) {
if(envelopes[j][0] < envelopes[i][0] && envelopes[j][1] < envelopes[i][1]) {
dp[i] = std::max(dp[i], dp[j] 1);
}
}
res = std::max(res, dp[i]);
}
return res;
}
};
